Difference Between Pressure and Stress
Pressure (Lithostatic
Pressure)
- Definition: A uniform force
applied in all directions, increasing with depth due to the weight of
overlying rocks.
- Effect:
- Promotes the formation of high-density minerals.
- Causes recrystallization but does
not result in deformation.
- Rocks remain unchanged in shape under
pressure.
- Role in Metamorphism: Influences mineral stability
and density without changing the rock’s structure.
Stress (Directed or
Differential Stress)
- Definition: A directional force
that is stronger in one direction than another, resulting in
deformation.
- Effect:
- Causes deformation of rocks, changing their
shape.
- Leads to the development of structures like
foliation and lineation.
- Minerals reorient along planes of weakness due to stress.
- Role in Metamorphism: Creates metamorphic
textures such as foliation and plays a key role in
strain (physical deformation).